Grinding and polishing pad



:"OOGDGQOQGGTSGQOO i Dec 5, 1967' G. E. BQNIN 3,355,843

GRINDING AND POLISHING PAD Filed Oct. l5, 1964 2 Sheets-$heet l /h `\/r\T 09009000000009L90 0 0000000000000 0002000000`0H000 l 0900000009000000000i000909000000 I l llllmw..

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00000000900000-0 00000000000000 000000000900000 000000000000O &00090090000000090 INVENTOR. George E Bon/n ATTORNEY Dec. 5, 1967 G. E.BONIN 3,355,843

GRINDING AND POLISHING PAD Filed Oct. l5, 1964 2 Sheets-Sheet 2 A TTORNE Y United States Patent C 3,355,843 GRINDING AND PLISHING PADGeorge E. Bouin, Addison, NX., assigner to Corning Glass Works, Corning,NX., a corporation of New York Filed (let. 15, 1964, Ser. No. 404,135Claims. (Ci. 51-397) ABSTRACT F THE DISCLSURE This invention relates `toan improved grinding and polishing pad, and more particularly to aflexible liner pad for finishing complex curvilinear surfaces withoutpoint loading.

`In the past, it has 'been customary to pumice and polish curvilinearglass-surfaces, such as TV panels and caps,` by utilizing'apneumatically inflated flexible cylindrical sleeve. The pneumatic sleeveis .rotated about its longitudinal axis and is positioned tocontact apanel or cap rotated about a vertical axis. When pumicing, the outersurfacev of .the sleeve lis provided with rubber or the like, whereaswhen polishing, the sleeve is provided with a felt outer surface.Although the pneumatic sleeve deformed to approximate the contour of theconvex rotating workpiece, and therefore provided some degree ofpolishing and pumicing,.it has not been completely satisfactory forvarious reasons. Gne disadvant-age resides in the fact that complete andcontinuons contact between the sleeve and the surface of the articlecannot be maintained, resulting in intermittent or partial contacttherebetween thus producing a rather low stock removal rate. A furtherdisadvantage of the pneumatic type of removal is the fact that itnecessitates extremely high power requirements for the amount ofmaterials removed. Further, point loading is otbained by the slappingpne-umatic sleeve which produces zone removal and which not only inducesbreakage, but alsoV results in surface aberrations.

Other methods utilized in the past to grind and polish curvilinearsurfaces .included the utilization of a hand pumice wheel. Not only isthis method extremely timeconsuming and expensive, but also due to humanerror the Aresults are not necessarily accurate.

The present invention obviates the above-noted disadvantages by theutilization of an improved flexible liner pad construction which iscontoured Iby a suitable pre-shaped support surface to complement thecurvature of the workpiece to be finished. A plurality of such linerpads are secured at an offset end to the support surface and areprovided on their back side with a plurality of fingers which maintainthe polishing surface in spaced-apart relationship with the supportsurface. In addition, the plurality of ngers provide the polishingsurface with uniform flexibility across its extent and accordinglyeliminates point loading and zone finishing by facilitating sectionaldeflection in those areas subjected to increased load. In addition, theplurality of fingers permits the ready dispersion of excess slurry fromthe working surface.

It thus has been an object of my invention to provide an` improvedgrinding and polishing means for finishing the contoured surface offrangible material.

An additional object of my invention has been to provide an improvedgrinding and polishing liner pad for finishing curvilinear ware surfaceswith improved removal rates without applying excessive local pressuresupon any portion of the ware.

A further object of my invention has been to provide a iiexible linerpad which readily conforms to the contour of a support surfacepre-shaped to complement the workpiece while maintaining the worksurface in spaced-apart relation from the support surface so as toabsorb sectional loading without deformation to the remainder of theliner.

These and other objects of my invention will become more apparent tothose skilled in the art from the following disclosure and accompanyingdrawings in which,

FIGURE l is a `bottom plan view of an improved liner pad embodying myinvention.

FIGURE 2 is a side elevational view shown in FIGURE l.

FIGURE 3 is an enlarged fragmental side elevational view of a liner padembodying my invention illustrating local deformation obtained uponsectional loading which does not deform the remainder of the liner, thusproviding an overall uniform surface arca contact irrespective ofirregularities in the workpiece surface.

FIGURE 4 is a somewhat schematic elevational view illustrating thepositionment of a plurality of liner pads shown in FIGURE l upon asuitably contoured support surface for complementarily finishing atelevision cap or the like.

Referring now to the drawings and particular-ly FIG- URES l and 2, aliner pad embodying my invention is shown at 10 having a main bodyportion 11 and an olfset connecting or `attachment portion 12. The mainbody portion has an upper working surface 13 which is adapted tocomplementarily engage the contoured surface of a workpiece to befinished. The under surface 14 of the body portion 11 is provided with aplurality of flexible tapered fingers 15 which extend outwardlytherefrom a distance equal to the offset of the connecting portion 12.As noted particularly in FIGURE 2, several rows of lingers, extendingalong the edge opposite the offset attachment portion 12, are shown asshortened fingers 16, for reasons which will become more apparenthereafter.

The offset attachment portion 12 is formed integrally with the bodyportion 11 and has a reinforcing or attaching bar 17 embedded therein.The pad 1@ may be of any suitable material providing a good workingsurface, although I prefer to utilize rubber or neoprene. In order tomaintain the attachment bar 17 in position within the connecting portion12, a plurality of anchor holes 13 are provided through the bar so as topermit the rubber or neoprene to liow therethrough during themanufacture. Further, a plurality of mounting or attachment holes 19extend through the connecting portion 12 to secure the liner pad 10 to asupport surface. A suitable enforcing fabric 3i), such as duck fabric,may be embedded within the liner material to provide added durabilityand reinforcement for tensile strength.

Since the liner pad has been designed primarily for finishingcurvilinear surfaces, both the hardness and flexibility of the workingsurface must be within defined limits to give maximum removal rateswithout imparting undesirable scratch patterns. These limits arecontrolled and maintained by utilizing rubber or neoprene type materialshaving a shore A durometer hardness of between about 50 to 90, and byspacing the plurality of exible fingers on about one-half inch tothree-quarter inch centers. By utilizing such combination of parametersit is possible to provide a working surface which may be preshaped by adesired support surface to conform to the general contour. of theworkpiece, while being liexible of the liner pad Lo conform toirregularities in the surface of such worknece.

The hardness of the rubber of neoprene utilized in the nody of the linerpad 1f), of course, cooperates with the iexibility derived from theplurality of fingers to proiuce the desired surface hardness presentedto the workniece. I have found that a working range exists between about50 and 90 shore A durometer and that optimum esults for televisionpanels are obtained with a hardness nf about 70. This optimum hardnessprovides maximum glass removal rate while leaving a surface which iseasily polishable. When the hardness reaches the upper limit of :heworking range, scratch patterns are developed in the surface of theworkpiece which are too deep to be effectively polished out; whereaswhen the hardness is below the lower limit, glass removal `rate is solow as to be virtually economically unfeasible. When used as a polishlngpad, the liner is provided with a felt working surface 13 which may besecured to the body portion 11 by my suitable means such as vulcanizing.

I have found that the center-to-center dimensions beween the fingers isan important factor in creating the desired flexibility. An optimumworking range exists between about one-half inch and three-quarter inchspacing when utilizing fingers having a diameter of approximatelyone-quarter inch. When the spacing is greater than about one inch, softspots develop on the working surface of the liner pad, which do noteffectively cooperate with the surface of the workpiece. When thespacing is less than about one-half inch, the working surface be- :omestoo rigid and defeats the tiexibility requirement. Each finger is apressure point which cooperates with the adjacent fingers to provide asynergistic effect for optimum surface support.

Referring now to FIGURE 3, the sectional loading of a liner pad 10, suchas might be occasioned by irregularities in the surface of the workpece,is schematically illustrated. It can be seen where a sectional orregional load L is applied to the surface 13 of the pad 10, the fingers15 beneath that section defiect to permit the sectional surface toconform to the irregularity while the remainder of the liner pad retainsits original configuration, which, as previously mentioned, conforms tothe general configuration of the remainder of the workpiece. Thisbuilt-in provision for sectional deflection not only inhibits pointloading of the workpiece but also zone grinding.

FIGURE 4 is a fragmental view schematically illustrating a mounting of aplurality of liner pads shown in FIGURES 1 and 2. The liner pads 10 aresecured to a suitable support member 2t) which may be supported by anysuitable means such as bearings 21 for rotation. The member is providedwith a pre-shaped support surface 22 for contouring the working surface13 of the pad 10 to substantially conform to the curvilinear contour ofa workpiece W. The workpiece may be mounted upon a suitable holder 23and rotated about a shaft 24.

As shown in FIGURE 4, the offset connecting portions 12 of the pads 10are secured to the support surface by screw means projecting throughattaching bars 17. If desired, end portions 17a of the attachment barwhich extend outwardly of the pad, may be provided with a suitableclamping device to secure the pad to the support surface. In order toform a continuous upper working surface the end opposite the connectingportion 12 is provided with shortened lingers 16, which overlie and restupon the adjacent offset connecting portion 12 to maintain the workingsurface 13 of the pads in a continuous free-flowing orientation. Inaddition, these shortened fingers 16 overlying the single end correctingportion cooperate with the passage formed between abutting pads toprovide a passageway for the removal of slurry from the work surface, sothat the excess slurry may fiow downwardly between the adjacent linerpads and between the shortened fingers 16 and along the fingers i5 to asuitable draw-off area in the support member.

Although I have disclosed the now preferred embodiments of my inventionit will be apparent to those skilled in the art that various changes andmodifications may be made thereto without departing from the spirit andscope thereof as defined in the appended claims.

I claim:

1. An improved liner pad construction for finishing contoured surfacesof a curvilinear workpiece which comprises, a body portion of fiexiblematerial, an offset connecting portion along one end of said bodyportion, an upper working surface formed on said body portion, aplurality of spaced-apart flexible fingers extending outwardly from alower surface of said body portion a distance equal to the offset ofsaid connecting portion, said fingers being formed integrally with saidbody portion and fiexibly maintaining said working surface inspacedapart relationship from a support surface so as to permit saidworking surface to conform to the configuration of the workpiece, anattachment bar embedded within said attachment portion to facilitate thesecurement of said body portion to a support surface, and said bodyportion together with its integrally formed fingers having a shore Adurometer hardness of between about 50 and 90.

2. A liner pad as defined in claim 1 wherein said plurality of fingersare equally spaced-apart on centers within the range of between -1/2inch and 1%, inch to impart uniform flexibility to the working surfaceand permit regional deflection of the working surface in response toirregularities in the surface of the workpiece while maintainingconformity with the remainder of the workpiece surface.

3. An improved liner pad construction for finishing contoured surfacesof a curvilinear workpiece which comprises, a body portion of fiexiblematerial, an offset connecting portion along one end of said bodyportion, an upper working surface formed on said body portion, aplurality of flexible fingers extending outwardly from a lower surfaceof said body portion a distance equal to the offset of said connectingportion, said fingers being formed integrally with said body portion andfiexibly maintaining said working surface in spaced-apart relationshipfrom a support surface so as to permit said working surface to conformto the configuration of the workpiece, an attachment bar embedded withinsaid attachment portion to facilitate the securement of said bodyportion to a support surface, and a plurality of fingers along an edgeopposite said connecting portion having a shortened length so as tooverlie the connecting portion of an adjacent liner pad and form adischarge passageway for excess slurry therebetween.

4. In combination with finishing apparatus having a contoured supportsurface, improved liner pad means for finishing curvilinear surfaces ofa frangible workpiece which comprises, a body portion of flexiblematerial, an upper working surface conformable to the contour of theworkpiece, and means formed integrally with said body portioncooperating with the contour of said support surface to conform the Worksurface to the general contour of the workpiece while permittingsectional deflection of the work surface to compensate forirregularities in the surface of the workpiece; said last-mentionedmeans comprising a plurality of spaced-apart flexible fingers formedintegrally with said body portion and extending outwardly from an undersurface thereof; and reinforced offset means for connecting said bodyportion to said support surface.

5. In combination with finishing apparatus having a contoured supportsurface, an improved flexible pad construction for finishing curvilinearsurfaces of a frangible workpiece which comprises, a body portion offiexible material, an upper working surface formed on said body portion,and means for fiexibly maintaining said working surface in spaced-apartrelation from said support surface while permitting said working surfaceto comple- 2,058,257 10/ 1936 Porteous 241-182 X mentarily contour thesurface to the workpiece; said exi- 2,178,728 11/ 1939 Schneible 51-8ble means comprising a plurality of spaced-apart resilient 3,236,010 2/1966 Evans 51--283 fingers extending outwardly from a lower surface ofsaid 34,001 12/1961 Mayall 15- 215 body portion and terminating at theirouter ends in a 5 2,672,637 3/1954 Allen 15 513 common plane; and anoffset attachment portion formed 3 100 312 8/1963 Williams 15 215 on oneend of said body portion and lying substantially n within the plane ofthe outer end of said resilient iingers FOREIGN PATENTS for attachingthe pad to said support surface. 625,105 6/1949 Great Britain ReferencesCited lo UNITED STATES P C. Primary Examiner.

730,900 6/ 1903 Fuller 241-182 D. G. KELLY, Assistant Examiner.

2,024,439 12/1935 Evans.

1. AN IMPROVED LINER PAD CONSTRUCTION FOR FINISHING CONTOURED SURFACESOF A CURVILINEAR WORKPIECE WHICH COMPRISES, A BODY PORTION OF FLEXIBLEMATERIAL, AN OFFSET CONNECTING PORTION ALONG ONE END OF SAID BODYPORTION, AN UPPER WORKING SURFACE FORMED ON SAID BODY PORTION, APLURALITY OF SPACED-APART FLEXIBLE FINGERS EXTENDING OUTWARDLY FROM ALOWER SURFACE OF SAID BODY PORTION A DISTANCE EQUAL TO THE OFFSET OFSAID CONNECTING PORTION, SAID FINGERS BEING FORMED INTEGRALLY WITH SAIDBODY PORTION AND FLEXIBLY MAINTAINING SAID WORKING SURFACE INSPACEDAPART RELATIONSHIP FROM A SUPPORT SURFACE SO AS TO PERMIT SAIDWORKING SURFACE TO CONFORM TO THE CONFIGURATION OF THE WORKPIECE, ANATTACHMENT BAR EMBEDDED WITHIN SAID ATTACHMENT PORTION TO FACILITATE THESECUREMENT OF SAID BODY PORTION TO A SUPPORT SURFACE, AND SAID BODYPORTION TOGETHER WITH ITS INTEGRALLY FORMED FINGERS HAVING A SHORE ADUROMETER HARDNESS OF BETWEEN ABOUT 50 AND 90.